Simaudio N HT's Xd - Manual (Page 9)

two XdS satellites and two XdW
powered bipole subwoofers. The
XdA’s equalization and filter para-
meters are held in nonvolatile mem-
ory, and can be updated via a USB
link using a Windows XP program
(provided you have Microsoft’s
.NET extension installed).
The three filters NHT sent me
were:
1) “flatterhighend.flt”—similar to the
original filter set, but, according to
Jay Doherty’s enclosed notes, “Flat-
ter above 10kHz; crossover point
between tweeter and midwoofer
moved up a hair (to 2.4kHz from
2.3kHz) to increase power handling;
reversed sub phase to try for better
sub/satellite integration”;
2) “150Hzcrossover.flt”—intended
for dual subwoofer use; keeps the
inverted subwoofer phase but moves
the crossover between the satellite
and subs from 110Hz to 150Hz to
enable the system to play louder; and
3) “150Hzxovereqto20Hz.flt”—
equalizes the subwoofers to be –3dB
at 20Hz instead of 26Hz.
There will be more filters to
come. According to Doherty, “We
are working on a linear-phase filter
to use between the satellite and sub-
woofer. LP filters require firmware
changes that we should be able to
implement by the time the first
room EQ software package is com-
plete. However, this will increase
total system processing time to about
18ms (from 7ms), so it might not be
usable with video.”
Kal had used only a single XdW
subwoofer, but as I intended to try
the filter sets with the higher cross-
over frequency, I asked NHT to send
me a second subwoofer. This increas-
es the system price to $7200.
Sound: As KR had described, set-
ting up the Xd system was quick and
easy. Unlike Kal, I had no ground-
loop problems, but this may have
been due to the fact that I used bal-
anced connections.
Preamp was first the Mark Levin-
son No.326S, connected to the
NHT XdA power amplifier with 15'
runs of Madrigal interconnects; then
an NHT Passive Volume Control,
connected with 6' runs of Canare
interconnects (the only balanced
cables I had with the necessary TRS
connectors). Digital source was
either a Mark Levinson No.31.5 CD
transport or a Technics DVD-A10
DVD player, hooked up to my ML
No.30.6 D/A processor via Kimber
Kable Orchid AES/EBU or Audio-
Quest SVD-4 S/PDIF datalinks,
respectively. The No.30.6 was con-
nected to the preamp with balanced
1m lengths of AudioQuest Cheetah.
I also used an Olive Symphony
media server to play back uncom-
pressed 16-bit AIF files via a TosLink
connection to the Levinson DAC,
and an Ayre C-5xe universal player
connected to the preamps with 15'
lengths of balanced Crystal intercon-
nects.
When he’d first set up the Xd, Kal
had remarked on a lack of integra-
tion between the satellites and sub-
woofer: “I measured an in-room
response that dipped several dB in
the upper-bass range centered on
130Hz. This detracted from the gen-
eral impression of weight, warmth,
and richness of sound. While the
crossover slope between the XdS and
XdW may be a very steep
48dB/octave at 110Hz, there is still
significant signal overlap between
the woofer and satellites; the posi-
tioning of the woofer is important. A
lower frequency, of course, would
compromise the power-handling
limits of the XdS’s 5.25" driver. I
found that moving the XdW for-
ward so that it was the same distance
from the listener as the satellites
filled in the integrated response, as
confirmed by instrument and ear.”
With first one subwoofer, then
two, and using the same filter set Kal
had used, I couldn’t eliminate the
upper-bass discontinuity no matter
how I experimented with subwoofer
positioning. The bass region was rich
and deep, but didn’t integrate suffi-
ciently well with the satellites. In
addition, while midrange tonalities
were reproduced with a delightful
lack of coloration, there was a some-
what reticent quality to the highest
frequencies. Whether or not these
problems bothered me was very
dependent on the music played.
I have written before about how
the choice of playback equipment
can change the choice of music
played. The discontinuity between
the satellites and subwoofers was
more audible with rock music, with
its ubiquitous four-in-the-bar kick
drum, than it was with classical
recordings. For the three weeks I
used the Xd system with the original
crossover filters, I found myself play-
ing a lot more symphonies and con-
certos than I had done with other
speakers that have recently occupied
my listening room.
The Xd’s extended low frequen-
cies were a much-appreciated benefit
with this kind of music, and the sys-
tem’s somewhat veiled highs were
much less of an impediment to musi-
cal enjoyment. I dug out discs that I
hadn’t played much, such as Michael
Tilson Thomas’ reading of Mahler’s
Symphony 3 (SACD, San Francisco
Symphony 821936-0003-2) and Seiji
Ozawa’s of Tchaikovsky’s Symphony
6 (SACD, Pentatone PTC 5186 107).
The double basses in the former’s
final movement had glorious weight
through the Xd system, though I
found the system’s midrange resolu-
tion very revealing of the wayward
intonation of the occasional sus-
tained brass chord in the latter. But
when I played Eric Johnson’s “Desert
Rose,” from Live from Austin TX (CD,
New West NW6084, recorded for
the Austin City Limits TV program),
the low bass just grumbled along
with the higher frequencies.
There was also something I
noticed with the toneburst track on
my Editor’s Choice compilation (CD,
Stereophile STPH016-2). This track
comprises equal-length tonebursts
that move from 32Hz up to 3.2kHz
in half steps, then back down again. I
created this signal to investigate
room and speaker-cabinet resonant
problems, but when I played it over
the Xd system, I was puzzled to hear
what sounded like very faint
“ghosts” accompanying the sinewave
bursts, almost but not entirely like
modulation noise. A puzzle, though
I did wonder if this phenomenon
had something to do with the veiling
I had noticed on music.
Time to install the new filter set. I
began with “flatterhighend.flt,” but
then changed to
“150Hzcrossover.flt” because the sys-
tem was still having difficulty han-
dling music with extreme amounts
of upper-bass energy. Stanley
Clarke’s double-bass solo on Airto
Moreira’s “Nevermind,” from our
Test CD 3 (Stereophile STPH006-2),
managed to shut down the left-chan-
nel satellite-woofer amplifier at the
volume I was finding appropriate for
the music. (The image lurched to the
right and a red light came illuminat-
www.Stereophile.com, January 2006
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